Search results for "Coactivation"
showing 10 items of 21 documents
Antagonist mechanical contribution to resultant maximal torque at the ankle joint in young and older men.
2007
Abstract A recorded muscular torque at one joint is a resultant torque corresponding to the participation of both agonist and antagonist muscles. This study aimed to examine the effect of aging on the mechanical contributions of both plantar- and dorsi-flexors to the resultant maximal voluntary contraction (MVC) torques exerted at the ankle joint, in dorsi-flexion (DF) and plantar-flexion (PF). The estimation of isometric agonist and antagonist torques by means of an EMG biofeedback technique was made with nine young (mean age 24 years) and nine older (mean age 80 years) men. While there was a non-significant age-related decline in the measured resultant DF MVC torque (−15%; p =0.06), there…
Mechanical impact of the antagonist muscles during maximal dorsiflexion is action mode dependent
2019
Maximal voluntary contraction (MVC) has long been considered as the best measure of neuromuscular performance. However, when MVC is paired with electromyographic (EMG) activity recording it has bee...
Coactivation at the ankle joint is not sufficient to estimate agonist and antagonist mechanical contribution
2009
The aim of this study was to assess, via an elec- tromyographic (EMG) biofeedback method, the mechanical con- tribution of both agonist and antagonist muscles during maximal voluntary contraction (MVC). We compared this original method with the MVC-EMGmax ratio and the torque/EMG relationship method, both of which are commonly used to estimate antago- nist torque. The plantarflexion (PF) and dorsiflexion (DF) MVCs were measured simultaneously with EMG activity of triceps surae (TS) and tibialis anterior in 15 young adults (mean age 23 years). Antagonist torques obtained from the torque/EMG relationship and EMG biofeedback methods appeared to be similar. TS antagonist torque had a major mech…
How the ankle joint angle alters the antagonist and agonist torques during maximal efforts in dorsi- and plantar flexion
2011
The aim of this study was to assess, via an EMG bio-feedback method, the ankle joint angle effect on the agonist and antagonist torques in plantar- (PF) and dorsi-flexion (DF). The isometric PF and DF maximal voluntary contractions (MVCs) torques were measured simultaneously with surface EMG activity of triceps surae (TS) and tibialis anterior (TA) muscles in 12 young adults (mean age 27) at five different ankle joint angles. Our results showed that: (i) The coactivation level does not properly reflect the mechanical effect of the antagonist muscle, (ii) TS antagonist torque significantly altered the DF MVC-angle relationship, whereas TA antagonist torque did not influence this MVC-angle re…
The Oculo-auricular Phenomenon in Brain-Stem Disease
1993
The oculo-auricular phenomenon (OAP), as described by Wilson in 1908 [26], consists of bilateral coactivation of external ear muscles during lateral gaze. Two ear muscles are innervated by motoneurons of the medial part of the facial nucleus [9, 25]: the transverse auricular muscle (TAM) (Fig. 1), which adducts and curls the helix of the auricle, and the posterior auricular muscle (Fig. 2), which moves the whole auricle backwards [3, 16, 22].
Muscular performances at the ankle joint in young and elderly men.
2005
The effect of aging on mechanical and electromyographic characteristics of ankle joint muscles was investigated in 11 young (mean age 24 years) and 12 elderly (mean age 77 years) males. Maximal and submaximal isometric voluntary torques were measured during ankle plantarflexion and dorsiflexion. Electromyographic activities of triceps surae and tibialis anterior muscles were recorded. The elderly group developed equal maximal dorsiflexion torques (42 vs 45 N.m, p >.05), but in plantarflexion, the elderly group was weaker (80 vs 132 N.m, p <.001) and presented a decreased twitch amplitude (11 vs 16 N.m) and lower coactivation (8% vs 15%) than that of the young adults. We established a linear…
Strength training in old age: adaptation of antagonist muscles at the ankle joint.
2005
The purpose of this study was to determine whether strength training could reduce the deficit in plantarflexion (PF) maximal voluntary contraction (MVC) torque observed in previous studies in older subjects relative to young adults. Accordingly, the effects of a 6-month strength training program on the muscle and neural properties of the major muscle groups around the ankle were examined. PF and dorsiflexion (DF) isometric MVC torques were measured and surface electromyographic activity of the triceps surae and tibialis anterior muscles was recorded. The strength training program was very effective in improving strength in PF (+24.5%), and it thus reduced the DF-to-PF MVC torque ratio; in a…
Electromyographic comparison of elastic resistance and machine exercises for high-intensity strength training in patients with chronic stroke
2016
To investigate whether elastic resistance training can induce comparable levels of muscle activity as conventional machine training in patients with chronic stroke.Comparative study.Outpatient rehabilitation facility.Stroke patients (N=18) with hemiparesis (mean age, 57 ± 8y).Patients performed 3 consecutive repetitions at 10 repetition maximum of unilateral knee extension and flexion using elastic resistance and conventional machine training.Surface electromyography was measured in vastus lateralis, vastus medialis, biceps femoris, and semitendinosus and was normalized to maximal electromyography (% of max) of the nonparetic leg.In the paretic leg, agonist muscle activity ranged from 18% t…
Motor unit discharge rate in dynamic movements of the aging soleus
2014
Aging is related to changes at the muscular level, leading to a decline in motor performance increasing the risk of falling and injury. It seems that the age-related changes in motor unit activation are muscle- and intensity dependent. The purpose of this study was to examine possible differences in soleus motor unit discharge rate (MUDR) in both isometric and dynamic contractions between young and elderly adults. 11 young (YOUNG) and 8 elderly (OLD) males participated in the study. The subjects performed isometric and dynamic plantar flexions while seated in an ankle dynamometer. The force levels studied were 10, 20, 40, 60, 80 and 100% of the isometric (ISO) MVC in ISO and 10, 20 and 40% …
Improved Postural Control after Behavioural Short Term Intervention in Patients with Psychiatric Dizziness
2009
Background:Patients with psychiatric dizziness often report subjective instability of stance and gait and fear of falls. They showed increased activity of their body sway in static posturography compared to normals (1, 2). Aim of the present study was to evaluate the efficiency of a behavioural therapy by static posturography.Methods:14 patients with psychiatric dizziness were included in the prospective study on static posturography to quantify the postural sway (sway path) during upright stance under different conditions. the psychosomatic examination comprised of standardized interviews (SCID-Interview) and a psychometric examination battery (SCL-90, VSS, VHQ). Results of static posturog…